switch to vite

web/config/setupTests.js

@@ -1,5 +1,6 @@
 import 'regenerator-runtime/runtime';
 import '@testing-library/jest-dom/extend-expect';
+import { server } from './server.js';
 
 Object.defineProperty(window, 'matchMedia', {
   writable: true,
@@ -13,6 +14,16 @@ Object.defineProperty(window, 'matchMedia', {
   }),
 });
 
-window.fetch = () => Promise.resolve();
-
 jest.mock('../src/env');
+
+// Establish API mocking before all tests.
+beforeAll(() => server.listen());
+
+// Reset any request handlers that we may add during the tests,
+// so they don't affect other tests.
+afterEach(() => {
+  server.resetHandlers();
+});
+
+// Clean up after the tests are finished.
+afterAll(() => server.close());